• The crash site of VH-SZS. (ATSB)
    The crash site of VH-SZS. (ATSB)

An Australian Transport Safety Bureau (ATSB) investigation report into an accident where an AS350 struck a powerline pole near Woomera in 2019 uncovered that the operator’s post-training supervision was ineffective in identifying that the pilot was using a modified stringing method.

Squirrel VH-SZS was stringing powerlines east of Woomera on 20 March 2019. While pulling the draw wire with a nose-high and rearward attitude, the helicopter’s main rotor blades struck one of the poles about 17 metres above the ground, bringing down the aircraft. The only occupant, the pilot, was killed in the crash.

"Shortly after being trained in powerline stringing operations, for unknown reasons, the pilot modified the stringing methodology," the ATSB discovered. "In addition to placing the helicopter at low level in the vicinity of the powerline poles, the modified methodology also exacerbated the uptake of dust.

"This, in combination with the position of the sun and the rearward attitude of the helicopter, likely reduced the pilots’ visibility of the pole and their situational awareness of it."

ATSB Director Transport Safety Stuart Macleod said the aircraft operator's procedures were found lacking when it came to post-training supervision.

“There were no requirements in the operator's procedures to provide any post-training supervision for powerline operations,” he said. “What supervision was provided was ineffective in identifying that a modified stringing method was being used by the pilot.”

The company has since put in place new procedures to strengthen post-training supervision.

“The mandated extension of command under supervision time, the introduction of periodic consolidation flight checks, and the mandated extension of mentoring time are all expected help better prepare newly trained pilots for solo operations and provide them with additional defences to the hazards associated with specialist flight tasks," Macleod said.

The investigation also highlighted that experience alone will not always prevent a pilot from having an accident. In this case, the pilot was a very experienced deputy chief pilot with nearly 6500 flight hours.

The full report is on the ATSB website.

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